The present invention relates in general to brake systems for land craft and in particular a brake system with antilock braking.
Hydraulic brake systems for land craft can be adapted to carry out, in addition to braking actions controlled by the driver, automatic braking actions which take place independently of an actuation of the brake system by the driver. Examples of automatic braking actions of this kind include braking actions for a traction control system (TCS), which prevent individual wheels from spinning when starting to drive through specifically braking the corresponding wheels, for dynamic stability control, in the case of which the vehicle behaviour is controlled within limits through specifically braking individual wheels, and for adaptive speed control, in the case of which, for example, predetermined speeds and/or distances from vehicles in front are observed through automatic braking of the vehicle.
It is usual, both with regard to braking actions controlled by the driver and with regard to automatic braking actions, to provide antilock braking in order to prevent wheels from locking during a braking action. In antilock braking mode the brake pressure in a wheel brake of a hydraulic brake system is modulated when locking or incipient locking of a corresponding wheel is ascertained. The brake pressure modulation takes place through pressure build-up, pressure maintaining and pressure reduction phases which alternate in a time sequence.
A problem in this respect lies in the fact that, in the case of braking actions controlled by the driver, hydraulic fluid in a master cylinder of a hydraulic brake system is generally caused to oscillate when carrying out antilock braking. This can lead to disturbing noises and to pulsating movements, corresponding to the oscillations, of a brake pedal which is provided to actuate the master cylinder.